Introducing Watch mode

Watch mode was the most-requested feature from people using ViewPort against a local dev server. Instead of re-running a crawl after every change, Watch mode polls the pages you already captured and re-renders just the ones that changed.

Under the hood it uses HTTP polling by default, with optional filesystem watching via chokidar when you point it at a project directory instead of a URL. Either way, the frames on screen update within a second or two of your save.

This pairs well with CI: run a normal crawl in your pipeline, and use Watch mode locally while you iterate on a fix.